Tube sound fuzz. What options did you use for yours??

[brett]

Hi.
When I built my tube sound fuzz (TSF), I put a 220 ohm resistor in the V+ line, only used 2 stages, and used smallish resistors (100k) and large caps (220pF) in the feedback loops. Hence my TSF has always sounded very "soft".  Before I try to make it more forceful (higher gain, more highs), I thought I'd ask what other people have done with their TSF type designs.

What configuration have you used and what have the results been like?  ie

• How many stages?
• If you used a supply voltage reduction resistor, what size was it?
• What size resistors in the feedback loops?
• What size capacitors in the feedback loops?
• Did you use the switchable rhythm/treble design and should it be a toggle or a stompswitch?

Thanks for your input.

[MartyMart]

Hi Brett, I've made three :
No 1 - exact Craig Anderton version, which I never got to work correctly
This could have been my "ignorance" as it was a while ago, I also had some
4049's without the right "UBE" suffix !!

No 2 - same, new layout ( vero ) and correct 4049UBE worked but had a wierd
"gain pot" which always worked "backwards"

No 3 - 100ohm from 9v, 220uf cap and 470n poly to ground, three stages, one with fixed 220k and two
gain pots of 500k for stages 2 & 3.
100pf caps across each stage.
This works quite well, if I could find a dual ganged 500k that would be GREAT !!
I tried a forth stage, but it was always TOO much and ended up howling and "mushy"
All in all, these are "fiddly" to get right but have a unique sound when they do work.
The three legged dog is similar and that's a great sound too.
I guess some more tone control/roll off between stages would be a benefit, I think that I
kept all those caps at either 47n or 33n .... can't remember !
Greetings,
Marty

[Nasse]

For that adjustable supply voltage I have seen one circuit somewhere maybe ETI or Practical Electronics that suggested just taking the voltage from  a viper of a pot, 10k perhaps. I sort of breadboarded it and it worked quite ok imho but I never bothered to box that extra pot.

The best sounding one I built for young bassplayer and i adjusted tsf circuit series and feedback caps and resistors by ear trial and errror till it sounded good with bass but can not remember what I used. Just for fun (wanted to know if it works) I wired all inverters in the chip parallel maybe 2 for first and 4 for last stage. It was in a very small box without bypass switch

I mostly turn the feedback resistor to low value. I have the "full tilt switch" and use it sometimes. I´m not happy with my TSF I should tune the caps or do something more radical, I know it can do a bit better, just now it does not sound good. Dont know if it is the chip I have changed it few times (smoked one once)

Every time I mail order some 4049ube chips I get buffered stuff instead

[WGTP]

Mutant Hot Harmonics.

First stage 1M pot
Second stage 22K to 47K resistor
Third stage 220K resistor with cap size to suit your taste
caps between stages large enough to NOT roll off too much bass.

It is claimed that the 4049 stages sound better when driven by an op amp or Jfet stage, than when driving themselves.  I thought by making the first stage honk, whatever unpleasantness was generated would be covered up by the next two stages distortion. 

For some reason, using a small (22K) resistor in the second stage made it brighter and livelier.   

[brett]

Hi.
Thanks everyone.
It seems like there's still some sorting could be done with this circuit.

Re:

It is claimed that the 4049 stages sound better when driven by an op amp or Jfet stage, than when driving themselves. 

I forgot to mention that I drove mine with a TL071 (non-inverting) with fixed gain of 10, followed by a volume control.
I might dump that volume control and replace it with a 1M pot in the first stage, like WGTP has.  Maybe reduce that 220 ohm resistor on the V+ line to 100 ohms or less, too.

cheers

[gez]

It is claimed that the 4049 stages sound better when driven by an op amp or Jfet stage, than when driving themselves. 

A lot of the comparisons are made between the Guitar Player circuit, with the op-amp 'buffer', and the 2 stage circuit comprised only of inverters.  A little unfair as you're not comparing like with like - the guitar player circuit's 1st stage has voltage gain so is, in effect, a three stage jobbie.  Add another stage to the Electronic Projects circuit and it would sound, with a little tweaking, a lot better.

I think the reason a lot of people perceive op-amp driven circuits to sound better is probably because you can drive the inverters slightly harder.  If you do some real tests for voltage gain you'll see that figures can be a lot lower than the ones quoted in data sheets, so if all your inverter 1st stage can give you is Av of 6, then sure an op-amp set for higher gain is going to sound different. 

I use mainly three stage circuits and they can sound really good, just need to do a bit of work with them...

[A.S.P.]

http://www.diystompboxes.com/smfforum/index.php?topic=47736.0

[MartyMart]

I forgot to mention that I drove mine with a TL071 (non-inverting) with fixed gain of 10, followed by a volume control.
I might dump that volume control and replace it with a 1M pot in the first stage, like WGTP has.  Maybe reduce that 220 ohm resistor on the V+ line to 100 ohms or less, too.

cheers

I found another "version" in the non-working pile !
I can't seem to find what it was ( looks different from every schem I have ) but it's an op amp buffer version
using a TL071 to drive the 4049.
I got it to work, but it's a bit "splatty" and when not driven hard it sounds awful !
Brett, perhaps you could point me in the right direction with it, I'm sure it's salvagable
I may also "ditch" the volume into the 4049 and use a 1M pot on stage one, have a 1M r there
at the 'mo
As a "high gainer" it works, but I'd like to be able to have some low/medium settings without
the " splatt/bias off" sound ..... ?

MM.

[brett]

Hi.

I got it to work, but it's a bit "splatty" and when not driven hard it sounds awful !

Hey, I made one just like that!  Maybe the same dodgy schematic lurking somewhere on the web.  If I recall, it was lacking a cap between the volume control and the 4049 input.  Hence at low volume levels the input bias was close to ground rather than floating at Vsupply/2.
Mine is a low gainer, with 2 stages of (100k resistor and 220pF cap).  If I was making a "soft" one again, I'd use 100k resistors, but reduce the caps to 150pF. That would increase the cutoff frequency from 7kHz to 10kHz.

thanks for the feedback
cheers

[A.S.P.]

same no-schem problem here

[MartyMart]

http://www.geocities.com/CollegePark/Library/1355/tsf.gif

Standard TSF ....

http://www.geofex.com/FX_images/mhtsf.gif

TSF with op amp front end 

There you go ASP .....

MM.

[Bernardduur]

I've made two: a Red Llama clone and a EHX Hot Tubes clone;

I liked the Hot Tubes way better than the Red Llama. Schematics are available.

[WGTP]

If something is too, splatty, I usually start by reducing the bass.  Using 3 stages with a cap at the end of each provides an opportunity for up to 18 db/oct. bass roll off.  Lots of possible curves by varying the cap sizes.  Might use two large caps that don't effect the bass much and then a smaller one to get it where you want it.

Frank Clark's Hot Harmonics used a Jfet stage and Mark Hammer's version used an op amp IIRC, to drive 2 or 3 stages of CMOS.

ROG has some variations.   

[A.S.P.]

http://www.diystompboxes.com/smfforum/index.php?topic=47736.0

[MartyMart]

the "splattyness" I suspected, would be misbiasing - that`s why I wanted to see that circuit with the missing cap...

about the wrong-way-pot: wire the wire going to one outer log to the other outer log instead!

And: ( we had that before...) the gain pot in the feedbackloop of the inverter doesn`t have a connection to ground...

And: Justin`s "CATSF" shows a 10M for "lead"; that leaves only a 10% regulation for the gain pot; I wonder if that is "Original C.A.", or ought to read 1M...

10M is in Craigs book, which i have.
Reversing the pot didn't solve it, it was just "full on" all the time either way ... really ?
The "wierd" one that I've found, doesn't have a connection to ground on the gain pot, and has 1M to VB and 2M2
to ground on pins 3 and 5 respectively ......

MM

[A.S.P.]

http://www.diystompboxes.com/smfforum/index.php?topic=47736.0

[MartyMart]

OK, solved my "wierd 4049"  - still have no idea what it is, so I guess it's mine now !!
.... well, I've changed just about everything ..... honest mom !!
It had no "pf" caps across the 4049, so I put some 470pf's on the back of the board
as that was the only space.
Changed both feedback r's to 200k's and now have nice gain range from almost clean
to quite rauchous !!
Also added new 10uf caps in and out of the 4049

So, it's the "Mr Tube Fuzz"  now   

MM.

[petemoore]

  The ones I've built have sounded realy Great...and have been problematic...
  That's why I want to try this again 
  A very gracious forum member sent me a 4049*Ube chip [I'm just horrible with names...please excuse me] for which anonymous thanks, the only kind I'm capable of is pronounced...
  I have one down there, I take voltages and see what I can figure out...

[Mark Hammer]

I've always preferred invertor-based overdrives that are preceded by a gain stage over units that used only the invertors.  Both Frank Clarke and Stellan Lehrberg seemed to agree with that in their respective followup designs (Clarke's "Hot Harmonics" series, and Lehrberg's "Slowfinger").  For whatever reasons,  I've found that dividing the work up between a front stage and the invertor chip itself yields a better quality sound.  Moreover, use of a preceding gain stage allows for tailoring the tone that will provoke the overload in the invertor in terms of low end and high-end rolloff.  For me, the magic seems to be in hitting the first invertor section with a hot signal that restricts the very top end (I rolloff around 5-7khz in the first stage).

The other thing I find I like is to use a voltage-divider pot between the initial gain stage and the invertor.  That pot, in turn, uses a bypass "bright" cap (I've been using .01uf straddled across a 10k pot, but you could use other values).  At lower gains and lower driving amplitudes (i.e., pot turned down, medium feedback resistors values in the invertor stages), you can get some nice Rickenbacker-through-Vox bite with single-coils.

I'm a bit too busy trying to finish up far too many projects that I'm far too committed to, so once again I'll politely ask that folks take a look at Charles Fischer's EM Fuzz project over at GGG as a possible candidate for their 4049 experiments.  I still have yet to hear comments from anyone who has built it.

[A.S.P.]

http://www.diystompboxes.com/smfforum/index.php?topic=47736.0